JS：“分享到”之类的悬浮框的运动原理（代码）

<!DOCTYPE html>
<html>

    <head>
        <meta charset="UTF-8">
        <title>只传一个参数</title>
        <style type="text/css">
            .div {
                width: 100px;
                height: 100px;
                background-color: chartreuse;
                margin-top: 50px;
                position: absolute;
                left: -100px;
                top: 0;
                cursor: pointer;
            }
            .div span{
                display: block;
                width: 20px;
                height: 50px;
                position: absolute;
                right: -20px;
                top: 50%;
                margin-top: -25px;
                background-color: coral;
                font-size: 10px;
                padding: 5px;
                -webkit-box-sizing: border-box;
                box-sizing: border-box;
            }
        </style>
        <script type="text/javascript">
        window.onload = function(){
            var oDiv = document.getElementById('div');
            oDiv.onmouseover = function(){
                start(0);
            };
            oDiv.onmouseout = function(){
                start(-100);
            };
        };
            var timer = null;
            //功能一抹一样的函数，参数越少越好。
            function start(iTarget) {
                var oDiv = document.getElementById('div');
                clearInterval(timer);
                timer = setInterval(function() {
                    var speed = 0;
                    if(oDiv.offsetLeft>iTarget){
                        speed = -10;
                    }else{
                        speed = 10;
                    };
                    if(oDiv.offsetLeft == iTarget) {
                        clearInterval(timer);
                    }
                    else{
                        oDiv.style.left = oDiv.offsetLeft + speed + 'px';
                    }
                    
                }, 30)
            };
        </script>
    </head>

    <body>
        <div class="div" id="div"><span>分享到</span></div>
    </body>

</html>
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